Many software virtualization products exist in the market today. The software virtualization products typically provide host software (for example, a control program) which creates a simulated computer environment, often referred to as a virtual machine, for so-called “guest software”. Guest software is often a complete operating system running as if it were installed on a stand alone hardware platform. Many different virtual guest machines may be simulated on a single physical host machine and each virtual machine can be activated, suspended, shutdown, cloned or moved as required. The effect of some of these activities can have a detrimental effect on the IT infrastructure of an organization. For example, if a virtual machine image is either suspended or shut down, the in-memory representation of the virtual machine is unloaded from the host machine. The content of the virtual machine is stored in a set of files on the filesystem of the host computer. This content may include vital resources and settings, such as the CPU, memory settings, devices, hard disk content etc.
In the example of a virtual machine image implemented by a virtual machine software provider, such as VMWare, the following are typically found:                a .nvram file which includes resource settings such as CPU, memory, Virtual devices etc.;        one or more .vmdk files each for simulated hard drive settings, for example the settings of a filesystem; and        a .vmx file with virtual machine customization settings.        
Accordingly, once the virtual machine image is completely shut down, it can be managed as appropriate by managing the above mentioned set of files. The management may include versioning, archiving, cloning, provisioning, etc. The files include all information relating to the operating system, all the installed software and related settings and any other appropriate information or data relating to the virtual machine.
Subsequently, if the virtual machine is restored and reconnected with the other physical and virtual machines on the network it is possible that they may include potentially harmful content. For example, security exposures, viruses, unlicensed software, events which have changed the files such that they are not in compliance with the current IT requirements for the network, etc. As a consequence, it is important to determine if the virtual machine image is “good” or “bad”. In addition, it is important to determine whether the virtual machine image includes the appropriate levels of anti-virus software, firewalls and security setting, license compliance tools and any other appropriate elements that indicates that the virtual machine will comply with the network. In order for this to be carried out, the virtual machine can consume significant resources from the virtual machine environment; and, if found to be non-compliant while being tested or verified, can trigger undesirable noncompliance events or security issues.
In the past, the typical scenario has been to restore and test a virtual machine in a closed virtual environment. This is time-consuming and requires effort before it is even decided whether it is worth repairing or updating the virtual machine rather than creating a new virtual machine image. The fact that the virtual machine is being restored and tested in a network environment can have negative impacts on the level of security and compliance especially during any security audits in respect of the network. In addition, in certain cases virtual machines to be used for demo purposes or commercial virtual applications can also be found and downloaded from the Internet. These machines are already configured and may not comply with the network concerned and the company security rules. Since more and more of these types of applications are occurring the above issues relating to security and compliance are being encountered more and more frequently.
US 2006/0136720 discloses a virtual machine scanning system that works on an active virtual machine created with a cloning operation from the original virtual machine or taking a snapshot of the running virtual machine. As the virtual machine is active the system does not solve the problem associated with compliance and security issues that arise when bringing a virtual machine back on-line after it has been dormant.
A web page associated with an off-line virtual machine servicing tool executive overview http://technet.microsoft.com/en-us/library/cc501231.aspx discloses an off-line virtual machine servicing tool and how it may be used in various business scenarios. Whilst this discloses some solutions to some problems mainly related to provide a way to automate the process of updating the virtual machines, it does not address all the issues associated with “reinstating” a dormant virtual machine back into a network.
Similarly, McAfee discloses the feature of security management of virtual machines in an off-line state http://www.mcafee.com/us/about/press/corporate/2008/20080227—181010_q.html. Again, this document solve certain problems that does not address all the issues associated with “reinstating” a dormant virtual machine back into a network.